TY JOUR TI RATIONAL PARAMETERS AND OPERATION MODES OF MODERN TRACTORS IN CONDITIONS OF VARIABLE CHARACTER OF EXTERNAL INFLUENCES KW tractor KW tillage KW rational parameters KW vari-able load KW design methods KW operating weight JO Bulletin of KSAU AU Zhuravlev, S.Y. PY 2018 IS PB Krasnoyarsk State Agrarian University